Personal effects accounting document

What is personal effects accounting documents (bsf186)? How important is this and how do we fill this document?

From what i gather, you need to list everything you are bringing with you into Canada. Don’t know why they require it but you have to itemize all. Even include all those that you shipping to Canada that has not yet gotten there. Someone said it is because you will have to pay tax on any other stuff y0\ou bring that is not bought there.